Cooling means for electrical inductive apparatus



May 9, 1967 A. M. LocKlE 3,319,202

COOLING MEANS 'FOR ELECTRICAL INIJUCTIVE APPARATUS Filed July 30, 1965 .44? w, V1 4222 FIG. l.

I WITNESS NVENTOR Qwf, W Arrhur M. Loekie Gn/ZM QM/Zoy ATTO RNEY United States Patent C) 3,319,202 COOLING MEANS FOR ELECTRICAL INDUCTIVE APPARATUS Arthur M. Loekie, Hickory Township, Sharpsville, Pa.,

assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed `luly 30, 1965, Ser. No. 476,032 4 Claims. (Cl. 336-61) This invention relates in general to electrical inductive apparatus, such as transformers, and more particularly to a new and improved heat .transfer or cooling system for cooling transformers disposed wholly or partially underground.

There is `a rapidly growing trend to underground electrical distribution systems, in which the `distribution transformers are disposed within an enclosure which is partial- 1y or totally underground. This not only improves the appearance of residential areas, but it increases system reliability by eliminating outages due to -adverse weather conditions and other factors detrimental to pole-type distribution. Underground electrical distribution systems, however, make it difficult to dissipate the heat generated by the transformers, making it necessary to derate the transformers, which adds substantially to the system cost. Many different methods of cooling the transformers have been proposed, but in general, they substantially increase the cost of the transformer installation, or complicate the enclosure structure and maintenance, or both, out of proportion to the improvement in cooling eiciency.

Thus, it would be desirable to provide a new and improved cooling system for su'bstantially improving the heat transfer rate or cooling efficiency of transformers disposed either partially or wholly underground, without complicating the enclosure structure and maintenance, and without adding substantially to the system cost.

Accordingly, it is an object of this invention to provide a new and improved cooling system for transformers disposed partially or wholly underground.

Another object of the invention is to greatly improve the heat transfer rate from transformers disposed partially or wholly underground, without unduly complicating the transformer enclosure and maintenance of Ithe transformer.

A further object of the invention is to provide a new Iand improved cooling arrangement for transformers disposed partially or wholly underground, which allows the transformer to operate without reducing its conventional rating, and without substantially increasing the cost of the installation.

Briefly, the present invention accomplishes the above cited objects by disposing a baffle or barrier member between the sidewalls of the transformer enclosure and the transformer, which preferably completely surrounds the transformer and which extends vertically between the means for covering the enclosure and a predetermined distance from the bottom of the transformer. Thus, the barrier forms two concentric air spaces between the transformer and the sidewalls of the enclosure, which are interconnected near the bottom of the transformer and which have access to the open ail through suitable openings in the covering means. The 'barrier is, at least in part, reective in character, and reflects the radiant heat energy from t-he transformer back towards the transformer, to conne it to the inner air space. The confinement of the radiant energy to the air space between the barrier member and transformer is contrary to the commonly accepted belief that this energy should be allowed to radiate to t-he enclosure w-alls, for maximum eiiiciency, but it has been found that the heat transfer rate is greatly increased by the improved system.

Further objects and advantages of ythe invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the invention, reference may be had to the following detailed description, taken in connection with the ,accompanying drawings, in which:

FIGURE l is an elevational view, partially in section, of a transformer mounted in an enclosure which is disposed in the ground, and a cooling arrangement for cooling the transformer which is constructed according to the teachings of this invention;

FIG. 2 is an elevational View, partially in section, of a transformer disposed Within an enclosure which is dispose'd in the ground, and a cooling system constructed according to another embodiment of the invention; and

FIG. 3 is an elevational View, partially in section, of a transformer disposed within an enclosure which is mounted in the ground, and a cooling system constructed according to another embodiment of t-he invention.

Referring now to the drawings, and FIG. 1 in particular, there is shown a iirst embodiment of the invention wherein underground electrical distribution is combined with streetlighting. 'More specically, FIG. 1 illustrates an improved heat transfer system 10 which includes a transformer 12 mounted within an enclosure 13. The enclosure 13 has a sidewall portion or vault 14 which is disposed in the earth 16. The sidewall portion or vault 14 lmay be formed of pre-cast concrete, or any other suitable material, and disposed within an appropriate opening or hole which is dug in the earth 16, which has crushed stone, gravel or Iany other suitable means 18 disposed therein to form the bottom of the enclosure 13 4and provide good drainage. The transformer 12 is disposed within the enclosure 13, and may be mounted on suitable supporting means, such as insulating blocks 20.

The cover means for covering enclosure 13 may be a transition vault 22 which may be formed of the same material as the vault 14, or any other suitable material. The transition vault 22 is suitably fastened to vault 14 by fastening means, such as nut and bolt combinations 24. The transition vault 22 slopes inwardly from the outer periphery of vault 14, to form a substantially dome shapehaving a flat mounting base for receiving a light standard or elect-ric light pole 26, which is secured to t-he transition vault 22 by suitable fastening means, such as nut and Ibolt combinations 28. The electric light pole 26 has a central opening 30 disposed therein, which is aligned with an opening 32 in the upper portion of transition vault 22. A lighting lixture (not shown) is secured to the up per portion of electric light pole 26.

Transformer 12 is preferably disposed within enclosure 13 such that a predetermined portion of the transformer extends above the suface of the ground 16, as shown in FIG. 1. However, this is not essential for practicing the invention; it merely facilitates the installation and maintenance of the transformer 12.

The primary or high voltage conductors 34 and 36 enter the enclosure 13 from underground, and may tenninate on the cover 38 of transformer 12 by right angle plug-in connectors 4l) and 42. The secondary or low voltage terminals 43, 45 and 47 may also be cover mounted, as shown, to facilitate maintenance from above, and electrical conductors 44, 46 and 48 may proceed from terminals 43, 45 and 47, upwardly through opening 32 in the transition vault 22 and to the lighting fixture (not shown) through the central opening 30 in the pole 26. Additional electrical conductors (not shown) may be connected to terminals 43, 45 and 47 and proceed underground to a load point for supplying the electrical requirements of a predetermined number of residences, or

other electrical loads.

Although underground electrical distribution installations, such as the installation shown in FIG. 1, present many operational and esthetic advantages, they do have the disadvantage of not disposing7 the transformer in the open air, and thus the cooling of the transformer becomes a major problem.A Derating the transformer is a costly solution, as are complicated heat dissipation systems, which hinder normal inspection and maintenance of the transformer, as well as the installation of the transformer.

FIG. 1 illustrates a new and improved heat transfer system 10 which is highly etlicient, has a low initial cost, and which presents little hindrance vto the installation, inspection and maintenance of the transformer. Spe-citically, the heat transfer system 10 comprises the addition of a barrier or wall-like member 50 around the transformer 12. The barrier member 56 is disposed between the transformer 12 and the sidewall portions of the enclosure 13 to form two concentric air spaces 52 and 54 :between the transformer 12 and the sidewall portion of enclosure 13. Thebarrier member 50 extends from the dome-like cover' or transition vault 22 to a predetermined distance from the bottom of the enclosure 13, thus allowing the air spaces 52 and 54 to join within the enclosure 13 near the bottom portions of the transformer 14. The barrier member 50 may be suspended from the transition vau'lt 22 by suitable fastening means, with the sidewall portions of transition vault 22 having a predetermined number of openings therein disposed on each side of the intersection of the barrier member 50 with the transition vault 22. For example, transition vault 22 may have openings 60 and 62 disposed therein below the intersection of the 'barrier member 50, and openings 64, 66 and 68 disposed therein above the intersection of the barrier member 50. Thus, air space 52 has access to the open air or atmosphere through openings 60 and 62, and air space 54 has access to the open air or atmosphere through openings 64, 66 and 68.

Barrier member 50 is preferably tubular in shape, but it may have any desired configuration consistent with the idea of providing a continuous barrier between the transformer 12 and the vault 14, which extends from the cover or transition vault 22'to a predetermined distance from the bottom 4of the enclosure 13, to provide two concentric air spaces which connect with one another near the bottom of the enclosure 1-3, and to the open air or atmosphere through openings in the cover or transition vault 22. One additional criterion of the barrier member 50 is that it be at least in part reflective in nature, and thus capable of reflecting radiant heat energy which impinges upon it back toward the transformer 12. Thus, Ibarrier 50 may be constructed of a solid or porous electrical insulating material having a metallic reflective coating disposed on its inner or outer surface, or incorporated within it,l or it may be constructed of a suitable metal, such as aluminum, which has at least one surface finished to render it highly heat rellective. In order to prevent the reflective means of the barrier 50 from being mechanically damaged, and in order to prevent the efciency of the reileetive means from being impaired by dirt and corrosion, it may be desirable to dispose the reflective means on the outer surface of the barrier member, with its reflective side facing inward, or it may be desirable to sandwic the reilective means between insulating and/ or protective layers of other material.

In the operation of the heat transfer system v10 shown in FIG. l, the transformer 12 generates heat energy when it is energized, which warms the air in the space 54 between the transformer 12 and the barrier 50. Because v of the reflective character of barrier 50, it reflects the radiant heat energy which it receives from the transformer 12 back toward the transformer. During the passage of the radiant energy from the transformer 12 to the barrier 50, and back toward the transformer, much of the heat energy is absorbed by the air through which itv passes, thus transferring at least the major portion of the heat generated by the transformer 12 to the air in space S4. The heated air inthe air space 54 rises, as shown by the arrows in FIG. l, escaping from the transformer enclosure 13 through openings 64, 66 and 63 in the cover or transition vault 22. As the heated air escapes from space 54, it is replaced by cooler air from space 52 by thermo-syphon action, with the cooler air entering the space 52 through openings 60 and 6 2 in the cover or transition vault 22.

Barrier 50 also substantially improves heat transfer by directing all of the cool air which enters enclosure 13 to the bottom of the enclosure, causing it to traverse a substantial portion of the outer surface of transformer 12 after it enters air space 54. Without barrier 50, the incoming air would traverse only a portion of the transformer 12, and some of the air would enter certain openings and immediately leave through other openings, without even traversing the transformer 12. Further, the :barrier member 50 prevents direct contact between the downward moving cooler air in the air space 52, and the upward moving heated air in the air space 54, which not on'ly eliminates turbulence which would result in a decreased air flow, but prevents the thermosyphon driving force from being weakened by direct contact of the cooler air with the heated air.

The reflective nature of barrier member 50 produces a plurality of desirable effects, which cooperate to substantially increase the eiliciency of the heat transfer system 10. The reflective barrier 50 shields the vault 14 and the surrounding earth ,16 from the heat generated by the transformer 12, which prevents long term drying out of the earth 16, with consequent impairment of cooling effect. The lower vault temperature cools the incoming air when the ambient air temperature is high and when cooling is the most important.

The reflective barrier 50 confines the heat energy radiated by transformer 12 to the air space ,54, whichis contrary to what has heretofore been considered desirable. However, it has been found that the system of FIG. 1 increases the net rate of heat transfer considerably and that the efficiency of heat transfer increases as the temperature of the transformer increases, when it is most needed. Experiments have indicated that the reflective heat barrier 50 increases heat transfer in the order of 25 to 35 percent.

The lpole 2.6, enclosure 13, which includes transition vault 22, vault 1 4 and the bottom portion 18 are all shown in cross section in FIG. 1, to more clearly illustrate the air flow in the heat transfer system 10. The transition vault 22 may be substantially an inverted cone in shape, or it may have a plurality of at connected sides. Suitable access doors may be disposed in the sidewall portion of the transition vault 22, which may be locked to prevent unauthorizedentry. The openings in the wall portion of the transition vault 22 may be disposed in the access doors, if desired, or in any other suitable location, with line screens and/or baffles (not shown) being suitably disposed relative to the air openings to prevent sticks and other foreign bodies from being poked through the air openings into the portion of the enclosure 13 occupied by the transformer 14. It should be noted that by making the opening 32 in the transition vault 22, and the opening 30 in the pole 26 large compared to the space occupied by the electrical conductors, and by providing air openings near the top of the pole 26, that an excellent draft or chimney effect is created which may add substantially to the air llow rate.

The general principles of the invention, illustrated in FIG. 1 and hereinbefore described, are also shown in the embodiments of FIGS. 2 and 3, with like reference numerals in the various figures indicating like components.

The embodiments of FIGS. 2 and 3 have been included to illustrate other types of enclosures that may be utilized with a heat transfer system constructed according to the teachings of the invention.

For example, if street lighting is not incorporated with the transformer 12, FIG. 2 illustrates an arrangement which differs from that of FIG. 1, only in the type of cover which is disposed over the vault or enclosure.

More specifically, the heat transfer system shown in FIG. 2 has the transformer 12 disposed within enclosure 13 such that a portion of the transformer 12 may extend for a predetermined distance above the level of the earth 16. Thus, a cover 80 is utilized which also extends above the earth. In this arrangement the cover 80 is secured to the vault 14 by suitable fastening means, such as nut and bolt combination 82, and the cover has a substantially vertical sidewall portion 84 which joins a substantially flat top portion 86. The barrier member 50 extends to and may be secured to the top portion 86 of the cover 80, with openings for the incoming air being disposed in the sidewall portions 84, and the openings for the exiting air being in the top portion 86 within the perimeter of the contacting barrier member 50. For example, openings 90 and 92 may be disposed in the sidewall portion 84, and openings 94, 96, 98 and 100 may be disposed in the top portion 86. As illustrated by the arrows, the heated air in air space 54 rises and exits through openings 94, 96, 98 and 100, and is replaced by cool air which enters cover 80 through openings 90 and 92, iiows downward through the air space 52 and then upward through the air space 54. The heat transfer system of FIG. 2 possesses the same advantages as the system described relative to FIG. 1.

In the embodiments of FIGS. 1 and 2, the transformer 12 may project partially above the ground level. In the event that it is not desirable to have any portion of the installation project above the ground level, the embodiment of FIG. 3 may be utilized. The embodiment of FIG. 3 differs from the embodiments of FIGS. 1 and 2 in that the transformer 12 is disposed wholly below ground level, thus allowing a fiat cover 110 to be utilized which is disposed over the vault 14 at ground level. In this embodiment, the barrier member 50 extends upward to the cover 110 and may be suitably aflixed thereto, with all of the air openings being through the cover 110. For example, the cool air may enter air passage 52 through openings 112 and 114, and the heated air may exit through the openings 116, 118 and 120.

In the embodiments of the invention shown in FIGS. l, 2 and 3, the barrier member 50 has been described as being fixed to the means for covering the enclosure 13. It is to be understood, however, that this is not an essential part of the invention. It is only necessary that the barrier member 50 extend to the cover means. It may actually be supported in the proper position relative to the cover means, the transformer, and enclosure sidewalls and bottom portion, by any suitable means, such as thin leg members which extend from the barrier member 50 to the bottom or sidewall portions of the enclosure, or to the transformer.

In summary, there has been disclosed a new and improved heat transfer system for electrical inductive apparatus that is wholly or partially disposed in the earth, which has a low initial cost, does not unduly complicate the installation, inspection and maintenance of the apparatus, and which substantially increases the rate of heat transfer from the inductive apparatus to the atmosphere.

Since numerous changes may be made in the above described apparatus and different embodiments of the in- Cil vention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative, and not in a limiting sense.

I claim as my invention:

1. A heat transfer system for electrical inductive apparatus comprising an enclosure disposed at least partially below ground level having a sidewall portion, a bottom portion, and cover means, electrical inductive apparatus disposed within said enclosure, barrier means having inner and outer sides disposed in spaced relation between said electrical inductive apparatus and the sidewall portion of said enclosure, said barrier means completely surrounding said electrical inductive apparatus, forming first and second concentric air spaces between said electrical inductive apparatus and the sidewall portion of said enclosure, with said first air space being between said barrier means and the sidewall portion of said enclosure and the second air space being between said barrier means and said electrical inductive apparatus, said barrier means extending from said cover means to a predetermined distance from the bottom portion of said enclosure to allow said first and second air spaces to join within said enclosure, said barrier means having at least one heat reiiective surface, which reects radiant heat energy from said electrical inductive apparatus back towards said electrical inductive apparatus, said cover means having a plurality of openings therein with certain of the openings joining the rst air space and certain of the openings joining the second air space, said electrical inductive apparatus heating the air within the second air space when it is energized and starting air circulation which includes air entering the first air space `through the openings in said cover means, moving downwardly through the first air space to the connection between the first and second air spaces, moving upwardly through the second air space, and exiting through openings in said cover means.

2. The heat transfer `system of claim 1 wherein said barrier means is formed of an electrical insulating material which includes metallic reiiective means, at least the side of said metallic reflective means which faces Said electrical inductive apparatus being finished to provide said at least one heat reective surface.

3. The heat transfer system of claim 2 wherein the metallic reflective means is disposed on the outer surface of said barrier means, with its heat reiiective side facing inwardly toward said electrical inductive apparatus.

4. The heat transfer system of claim 2 wherein the rnetallic reflective means is disposed between the inner and outer sides of said barrier means, with its heat reflective side facing inwardly towards said electrical inductive apparatus.

References Cited by the Examiner UNITED STATES PATENTS 342,552 5/1886 Westinghouse 336-90 X 3,118,968 1/1964 Mousson 174-179 3,225,224 12/ 1965 Rydbeck 317-103 X FOREIGN PATENTS 506,796 10/1951 Belgium.

701,486 1/71931 France. 1,165,708 3/ 1964 Germany.

LEWIS H. MYERS, Primary Examiner.

T. I. KOZMA, Assistant Examiner. 

1. A HEAT TRANSFER SYSTEM FOR ELECTRICAL INDUCTIVE APPARATUS COMPRISING AN ENCLOSURE DISPOSED AT LEAST PARTIALLY BELOW GROUND LEVEL HAVING A SIDEWALL PORTION, A BOTTOM PORTION, AND COVER MEANS, ELECTRICAL INDUCTIVE APPARATUS DISPOSED WITHIN SAID ENCLOSURE, BARRIER MEANS HAVING INNER AND OUTER SIDES DISPOSED IN SPACED RELATION BETWEEN SAID ELECTRICAL INDUCTIVE APPARATUS AND THE SIDEWALL PORTION OF SAID ENCLOSURE, SAID BARRIER MEANS COMPLETELY SURROUNDING SAID ELECTRICAL INDUCTIVE APPARATUS, FORMING FIRST AND SECOND CONCENTRIC AIR SPACES BETWEEN SAID ELECTRICAL INDUCTIVE APPARATUS AND THE SIDEWALL PORTION OF SAID ENCLOSURE, WITH SAID FIRST AIR SPACE BEING BETWEEN SAID BARRIER MEANS AND THE SIDEWALL PORTION OF SAID ENCLOSURE AND THE SECOND AIR SPACE BEING BETWEEN SAID BARRIER MEANS AND SAID ELECTRICAL INDUCTIVE APPARATUS, SAID BARRIER MEANS EXTENDING FROM SAID COVER MEANS TO A PREDETERMINED DISTANCE FROM THE BOTTOM PORTION OF SAID ENCLOSURE TO ALLOW SAID FIRST AND SECOND AIR SPACES TO JOIN WITHIN SAID ENCLOSURE, SAID BARRIER MEANS HAVING AT LEAST ONE HEAT REFLECTIVE SURFACE, WHICH REFLECTS RADIANT HEAT ENERGY FROM SAID ELECTRICAL INDUCTIVE APPARATUS BACK TOWARDS SAID ELECTRICAL INDUCTIVE APPARATUS, SAID COVER MEANS HAVING A PLURALITY OF OPENINGS THEREIN WITH CERTAIN OF THE OPENINGS JOINING THE FIRST AIR SPACE AND CERTAIN OF THE OPENINGS JOINING THE SECOND AIR SPACE, SAID ELECTRICAL INDUCTIVE APPARATUS HEATING THE AIR WITHIN THE SECOND AIR SPACE WHEN IT IS ENERGIZED AND STARTING AIR CIRCULATION WHICH INCLUDES AIR ENTERING THE FIRST AIR SPACE THROUGH THE OPENINGS IN SAID COVER MEANS, MOVING DOWNWARDLY THROUGH THE FIRST AIR SPACE TO THE CONNECTION BETWEEN THE FIRST AND SECOND AIR SPACES, MOVING UPWARDLY THROUGH THE SECOND AIR SPACE, AND EXITING THROUGH OPENINGS IN SAID COVER MEANS. 